Short duration electrical switch



June 2li? T1966 E. s. SMITH 3,257,536

SHORT DURATION ELECTRICAL SWITCH Filed Aug. 29, 1963 5 Sheets-Sheet 1rfv/32 QMS 52 L \32 24 I l l ,9 se f 24 l n, i \\O/ ,I9 6 A f /o/lg '9El: CYL/'9 se f le(I 36- 56 54 A 58 se 44 46 Nm 4e 42 I9 --rs 6 x I4 i1I D 4o l 52 INVENTOR. Fig 5 EUGENE s. SMITH ATTORNEY June 21, 1966 E. s.SMITH SHORT DURATION ELECTRICAL SWITCH 5 Sheets-Sheet 2 Filed Aug. 29,.1963 INVENTOR.

EUGENE s. SMITH ATTORNEY June 21, 1966 E. s. sMlTH SHORT DURATIONELECTRICAL SWITCH 5 Sheets-Sheet 3 Filec'l` Aug. 29, 1963 muws mvENToR.

EUGENE s.smTH lav/@MMM ATTORNEY United States Patent O This inventionrelates to electrical switches of the type I in which the intended ordesired duration of make or break is relatively short. In particular ithas t -do with switches of a type which may be actuated, for the mostpart, by finger pressure, and since retrograde movement in such anoperation involves a time lag due to inertia, and

motor responses in the body senses, it is an object of the invention toprovide -a switch in which the release, after contact, is automatic, andtherefore rapid, and not depend-ent upon reversal of theswitch-actuating force, whether the latter is manually applied, or bymechanical means.

e More particularly, it is an object to provide an vautomaticallyopenable switch comprising a spring-biased, reciprocating operating rod,with guide means for lateral displacement in a path of circuitoustravel.

In still greater particular, it is an object to provide a switch havinga reciprocating operating rod, normally spring-biased to idle position,a guide track for constraining part of said rod to a circuitous pathincluding a switch contact in its m-otion of reciprocation, and opposedspring means acting laterally on said rod, at spaced points along itslength and effective sequentially during reciprocation.

These and other objects, which will be apparent, are attained by thepresent invention, a preferred form of which 'is described in thefollowing specification, as illustnated in the drawing, in which;

FIGURE 1 is an axi-al, sectional View through a switch unit, showing oneof the separate halves of the casing in elevation,

FIGURES 2 and 3 are views similar to FIGURE 1, showing successivepositionsof the push rod,

FIGURE 4.is a vertical section, axially of a portion of the push rod,taken on the plane of the line 4-4 of FIG- URE l, v

FIGURE 5 is -a view similar to FIGURE 4, taken on the plane of the line5--5 of FIGURE 2,

FIGURES 6 and 7 :are transverse, sectional views, taken on the Vplanesof the lines 6-6 and 7--7, respectively, of FIGURE 1,

FIGURES -8, 9 and 10 are views similar to FIGURES 1, 2 and 3, showing amodified form of actuator,

FIGURES 11, 12, 13 and 14 are `sectional views, taken onthe planes ofthe respective lines 11.-11, 12.-12, 13-13, and 14-14, of FIGURE 8,

`FIGURES 15 and 16 `are'views siimlar to FIGURES 1, 2 Iand FIGURES 8, 9,and

` FIGURE 17 is an enlarged View of the area indicated by lthedashed-line, rectangular loop 17, in FIGURE 16.

Referring to the drawings by characters of reference there is shown `aswitch box 10, suitably secured, as by long screws 12, to the housing14, containing an actuating unit for the switch. As seen in FIGURE 6,the housing 14 is composed of two halves 16, 18, separated along amedial, longitudinal plane, and one being constructed in mirror imagerelation to` the other, and having bores 19 for connecting the partswith screws or bolts. As seenin FIGURE 56, the upper part of housing 14is square in cross section, with a chamber 2t), circular in crosssection, while the lower part is rectangularly oblong in cross section,being narrower than the upper part, and has an inner chamber 22,rectangular in section, .and geometrically similar to the outer crosssection of the lower part.

Patented June 21, 1966 ICC Upper chamber 20 of the housing communicateswith the exterior through an elongate, gener-ally elliptical slot 24,and communicates with the lower chamber 22, through a similar slot 216,formed in a septum 28, which separates the two chambers. A push rod oractuator 30, with push button head 32, extends from outside the housingthrough slot 24, chamber 20, and slot 26, into chamber 22, and has amiddle, reduced portion 34, deiining a shoulder which serves as a stopfor a washer 36. A compression coil spring 38, surrounding reducedsection 34 of the push rod, acts between septum, or bridge, 28, andwasher 36, urging the latter normally against the top wall of thehousing, containing slot 24, which represents the uppermost, or idleposition of the push rod.

As the push rod is urged downward, its bottom end, which moves whollywithin the lower chamber 22, is constrained to lateral components ofmotion, and consequent movement in a closed loop, by cam track andfollower means, the former provided by grooves inthe chamber, and thelatter by lateral protuberances on the push rod. Thus, opposite walls ofchamber 22 are each provided with a grooved channel, of larcuate crosssection, and g-enerally triangular in overall form, comprising la firstsection 40 defining a first path, which accommodates the push rod end onits downward stroke, a short, horizontal section 42 defining a secondpath, 4at the bottom of the stroke, and a generally vertical section 44defining la third path, which guides the return stroke upwards, andwhich merges at the .top of the stroke with the initial passage 40,where the push rod is positioned for the next cycle of operation. Thegrooves just described leave, in each wall, a central island, or'boss,46. Preferably this boss will be cut away along a line 4S (FIGURES 1andI 2) to provide a flared, lower end, or mouth, for `the return groove44, to ensure entry of the follower into the return groove.

The follower means on the push rod are constituted by a pair ofoppositely disposed, laterally Iextending pins S0, near the lower end oflower portion 52 of the push rod, with hemispherical outer ends yadaptedto substantially mate with, and nest in, the cam grooves, for slidingmovement therealong. In the cam and follower action, the lower end ofthe push rod is urged laterally, by spring action into groove 40 on thefirst part of the cycle, and in the opposite direction by another springmeans, -along bottom groove 42, for entry into return groove 44, at thebottom of the initial stroke. Thus, a double-headedl pin 54, slidable ina lateralopening in a boss 56 on the housing, has la compression spring58 in surrounding relation to its shank, which urges it into contactwith lower portion 52 of the push r-od on a line passing through theupper junction of the two vertical grooves, so that the push rod willalways be urged into groove 40 upon initial down- 50 are engaged ingroove 40, this bias becomes unnecessary, .and the push rod moves awayfrom pin 54 which remains at the innermost position of its slidingmotion, with its outer flange 60, abutting the housing.

The lower end S2 of the push rod carries a metallic, hemispherical head62, as an insert, which isintended to make simultaneous,circuit-closing-contact with the terminal prongs 64, of leads 66,secured within switch box 10 by bolts 68, serving as binding posts forthe circuit leads. As seen in FIGURES 2 and 5, -this circuit-closingcontact by the push-rod head is accomplished when the followers 5t) a-renear the bottom of the stroke, and positioned for entry into the short,lower, transverse grooves 42. At this stage the lower end of the pushrod` is subject to a spring bias engendered by its contact with anddepression of a d-ouble-headed pin 70, slidable in suitable openings inhousing 14 and switch box 10, and having an inner, domed head 72, underthe constant bias of a surrounding 3 compression spring 74, whichmaintains the head 72 normally in the path of travel of the push rod end52 along Ithe path of grooves 40. For guaranteed operation, theconducting head 62 should make bridging contact of the prongs 64 justprior to' arrival of the follower pins to a position permitting entranceinto the bottom groove 42, with the prongs yielding in aV slight degreeof bend to permit' completion of the downward stroke for such entry.This interval of pre-contact may, -of course, be extremely b-rief, andupon arrival of the followers at the entry position, the spring 74 isimmediately effective to move the followers across lower grooves 42,thus opening the circuit, in spite of the fact that finger pressure onthe push rod is still effective. Thereafter, the push rod is dev barredby spring 74 from either closing the circuit, or reentering groove 40,and after cessation of the depressing force on lthe push rod head,spring 38 returns the push rod upwardly, with grooves 44 guiding it tothe starting position of the switching cycle, and energizing spring 58in the process. In this upward movement, the guidance of the followersinto the return grooves 44 is aided by the ared configuration of thelower ends of these grooves.

The modification illustrated in FIGURES 8 through 14 is generallysimilar to that just described in respect to the push rod andclosed-loop cam grooves, but in lieu of a bridging of leads by the pushrod, the l-atter serves to actuate a conventional `push -p-in 84, whichis normal component of a commercially available switch, such as amicro-switch. Thus, the housing 76 is generally similar to housing 14,and carries a spring-urged push rod 78, with a lower, spherical head 80,adapted to ride cyclically ina triangular configuration of cam groovessimilar to those in FIGUREl 1.

The switch box 82 has the protruding, push pin 84, controlling a circuitrepresented by terminals 86, 88, and this push pin in actuated onacontact byra leaf spring 90, secured to an inner wall of the lowercompartment of housing 76, by rivets 92, and extending across thegrooves representing the path of downward movement of the push rod head80. For certainty and lrapidity of action, the leaf spring 90 may havethe assistance of a push pin 94 slidably mounted -in a tube 96 in switchbox 82, and extending into housing v76 through an opening therein, andbacked by a compression spring 98, whichV urges theA leaf spring 90 toits normal position, athwart the cam grooves.

It will be seen that, as in the case of the other modification, pressureon the push rod 78 will result in movement of round head 80 downwardalong the right hand pair of grooves, in which movement the leaf spring90 is swept aside, against the spring pressure on pin 94, with switchaction being effected by pin 84, after contact by leaf 90, andimmediately prior to ar-rival of head 80 a-t the position shown inFIGURE 9, where it is ready for entrance into the bottom groove. At thisposition, shown upon FIGURE 9, both the leaf spring 90 and thespringpressed pin 94 urge the head 80 along the bottom groove, and inthis movement the pin 84 is released. As in the case of the othermodication, duration of the switch action is momentary only. Alsosimilarly to the other modification, the head 80 returns up the lefthand grooves, to sta-rting position, after release of pressure from thehead of push rod 78. FIGURE shows the positions of the parts after head80 has been moved to its extreme leftward position as viewed uponFIGURES 8, 9 and 10, and is about to be elevated to the startingposition of FIGURE 8 and 11 by the urge of the coil spring surroundingrod 78.

The modification shown in FIGURES through 17, which represents apreferred embodiment of the invention, differs from the first twodescribed modifications in providing an improved application of forcevectors, in the wiping action on the laterally applied, spring-biasingmeans, and in providing a yieldable reciprocating member in theswitch-closing mechanism, whereby adjustment of the switch gap lispermissible. Yet another difference resides in the integral constructionof the push rod housing and the switch box, whereby all the mechanismmay be laid in one half of the shell, and the other half then laid on,and secured by bolts or screws.

Thus, the push rod housing of FIGURES 15 through 17 is integral with theswitch box 102, in each of two shell halves, secured together by fivescrews or bolts through bores 104. Push rod 106 is substantially thesame in structure, location and function as rod 30 of FIGURE l, and thecam grooves in which it is guided are the same as the grooves 40 through44 of FIGURE 1. The elements `differing from what is shown in FIGURE 1will be best understood with reference to enlarged view FIGURE 17.Therein it will be seen that the lower, lateral, b-iasing means 10S7 isnot contacted directly by the head integrally fixed with the lower endof rod 106 but, to the contrary, by a swingable leaf or slab 112,pivoted at the medial partition 114, and extending downward to aposition where its lower end portion is in covering relation to theouter end of the reciprocator 108, which latter will presently bedescribed. For pivotal mounting, the leaf 112 has an integral,cylindrical, upper head 116, with axis transversely disposed, whichconstitutes a set of trunnions, the ends of the head being journalled insuitable bores in the meetingrhalves of partition 114. A cylindricalsegment 118, integral with and depending from the lower surface of thepartition, serves the dual function of holding the head against downwardremoval from its trunnion mounting, and of providing a stop, limitingclockwise movement of the leaf. By this arrangement, it will be seenthat contact of the push rod with the reciprocator 108 in a manner toprovide unfavorable angles of the applied force vector with respect tothe axis of the reciprocator, is avoided, and the relatively long,effective radius of leaf 112 gives a force direction which issubstantially axial as to the reciprocator 108, and substantiallytransverse to the cam groove, for equally favorable contact with thepush rod. Although the upper biasing means has been shown asstructurally similar to that of FIGURE 1, it will be understood thathere, also, the intervening, swinging member may be employed toadvantage.V

The switch mechanism in the box 102 may be completely assembled, apartfrom the switch housing, and then deposited, as a unit, in theappropriate niches in one of the housing halves. This mechanismcomprises a fixed, but adjustable contact portion 122, and a movablecontact portion 124. The fixed portion is based on a metallic bushing,or nipple, 126, axially threaded at its inner end to receive a threadedshank 128, extending within the chamber of box 102, and carrying at itsinner end therein, a disc-form head 130, constituting one of thecircuit-closing, electrical contacts. The position of head is`adjustable by turning of threaded shank128, for which purpose the outerend of the shank hasa slot 132 to accommodate a screw driver. The shank128 is locked in adjusted position by means of a screw 134, in athreaded counterbore in nipple 126, and a lead terminal 136 is held incontact with the nipple by means of a nut 138 on screw 134.

The movable portion of the switch contact mechanism comprises a contactdisc 140, similar to disc 130, screwconnected to a strip 142 offlexible, conducting material such as braided cable, or fiat leaf, andthe flexible strip is in turn screw-connected to a conductor bar 144,embedded in a notch in the box wall, and having a transversely bent,outer end 146, bored to receive a securing screw 148, to which issecured the other terminal, 150, of the circuit leads.

Inner contact disc 140 is part of a reciprocating system,l

tition wall 154 of the housing, and disc 140 has an integral shank 155,slidably mounted in the tube 152, the sliding movement of the sha-nkbeing limited by a laterally disposedpin 158, carried by the shank, theends of which extend through oppositely disposed, longitudinal slots160, in the tube 152.

Wall 154 has a counterbore 162 accommodating a collar 164 on tube 1.52,which is engaged by a compression coil spring 166, surrounding the tubeand constantly biasing the tube in a direction inwardly of the housing,that is, away from the position of switch contact. This inward movementis limited by the pin 158, engaging against a boss 168 on wall 154,`which stops the domed, inner end of the tube, and the leaf 112 which itpushes, at a position in the path of push rod 166. (See FIGURE 15.) Inthis position the switch points, or discs, are open, and the telescopingparts of the plunger 108 a-re extended to their fullest through actionof a compression spring 170, carried in the blind passage of tube 152,and acting against shank 156. This expanding movement of adjustment islimited by contact of pin 158 with the outer ends of slots 160. It willbe seen that in the case where the adjustment of contact disc 130 wouldnot permit full movement of the rrider, sufficient to clear the camgroove, the inner spring 170 will yield, permiting telescopic collapseof the parts to the extent necessary for such clearance.

While certain embodiments have been shown and described, Ivariousmodifications will be apparent, in the light of this disclosure, and theinvention should not, therefore, be deemed as limited, except insofar asshall appear from the spirit and scope of the appended claims.

I claim:

1. In a device for momentarily closing an electric circuit, a circuitcloser, an actuator having a longitudinal axis, means mounting saidactuator for movement along said axis and for pivoting in a planecontaining said axis, means engaging and positively guiding one end ofsaid actuator, in succession, from a point of beginning in a rst pathalong said axis, a second path transversely of said axis, and a thirdand return path along said axis to said point of beginning, and meansoperated by and in response to movement of said end of said actuatorsubstantially into the intersection of said rst and second paths toactuate said circuit closer.

2. The device of claim 1, and means urging said actuator along said axisaway from said second path to position said one end thereof at saidpoint.

3. The device of claim 2, and means engaging said actuator at said pointand urging said one end thereof into said first path.

4. The device of claim 2, and means engaging said actuator at saidintersection of said rst and second paths and urging said one endthereof into and along said second path.

5. In a device for momentarily actuating a circuit closer, a casinghaving spaced side walls, an actuator having a longitudinal axis andextending through an opening in said casing, first means fixed with atleast one said side wall and engaging and positively guiding the end ofsaid actuator Within said casing, in succession from a point ofbeginning, along a first path along said axis, a second pathtransversely of said axis, and a third and return path along said axisto said point of beginning, second means yieldingly urging said actuatoralong said axis to position said end thereof at said point, and meansoperable to actuate a circuit closer by and in response to movement ofsaid one end of said actuator into the intersection of said first andsecond paths, against the urge of said second means.

6. The device of claim 5, meansengaging said actuator at said point ofbeginning and urging said end thereof into said first path, and meansengaging said actuator at said intersection of said first and secondpaths and urging said end thereof into and along said second path andinto said third and return path.

7. The device of claim 5, said first means comprising first and secondclosed channels each in a respective one of said side Walls and eachhaving a section defining respective ones of said paths, and meanscarried by said rod adjacent said one end thereof for guided movement inand along said channels.

8. A device for momentarily actuating a circuit closer, comprising acasing having spaced side walls, a rod having a longitudinal axis andextending into said casing between said walls, means mounting said rodfor pivoting in a plane between said walls and containing said axis andfor movement relatively to said casing along said axis, there beingfirst and second closed channels each in a respective one of said wallsand each defining a first path extending from a point of beginning,along said axis, a second path transversely of said axis in said plane,and a third-path returning to said point, follower means carried by saidrod adjacent the end thereof within said casing and slidably fittingsaid channels for guided movement thereby, spring means yieldinglyurging said rod into position locating said follower means at said pointof beginning, spring means engaging said rod and urging said followermeans when at said point, into said first path, spring means engagingsaid rod and urging said follower means when at the intersection of saidlirst and second paths, into and along said second path and into saidthird path, a circuit clgser xed with said casing and including a partprojecting into said casing, said part being momentarily engaged toclose and open a circuit by and in response to movement of said followermeans substantially into the intersection of said first and secondpaths.

References Cited by the Examiner UNITED STATES PATENTS 1,732,577 10/1929Durdin 20o-s4 2,083,118 6/ 1937 Goldstone. 2,151,858 3/1939 Maysip etal. 74-151 3,142,743 7/1964 Borges 200--160 3,144,537 8/1964 Kiwi. v

ROBERT K. SCHAEFER, Primary Examiner'.

KATHLEEN H. CLAFFY, Examiner.

D. SMITH, I R., Assistant Examiner.

1. IN A DEVICE FOR MOMENTARILY CLOSING AN ELECTRIC CIRCUIT, A CIRCUIT CLOSER, AN ACTUATOR HAVING A LONGITUDINAL AXIS, MEANS MOUNTING SAID ACTUATOR FOR MOVEMENT ALONG SAID AXIS AND FOR PIVOTING IN A PLANE CONTAINING SAID AXIS, MEANS ENGAGING SAID POSITIVELY GUIDING ONE END OF SAID ACTUATOR, IN SUCCESSION, FROM A POINT OF BEGINNING IN A FIRST PATH ALONG SAID AXIS, A SECOND PATH TRANSVERSELY OF SAID AXIS, AND A THIRD AND RETURN PATH ALONG SAID AXIS TO SAID POINT OF BEGINNING, AND MEANS OPERATED BY AND IN RESPONSE TO MOVEMENT OF SAID END OF SAID ACTUATOR SUBSTANTIALLY INTO THE INTERSECTION OF SAID FIRST AND SECOND PATHS TO ACTUATE SAID CIRCUIT CLOSER. 